Total dimensional stability compensation system and method for magnetic tape drive

ABSTRACT

A tape drive includes a first tape head, a first actuator assembly, a second tape head, a second actuator assembly, and a controller. The first tape head includes two first servo elements that each read one of two servo tracks, and a first read/write element that one of reads data from and writes data to a first data track. The first tape head is positionable at a first base head rotation angle. The first actuator assembly selectively rotates the first tape head from the first base head rotation angle to a first adjusted head rotation angle. The second tape head includes two second servo elements that each read one of the two servo tracks, and a second read/write element that one of reads data from and writes data to the first data track. The second tape head is positionable at a second base head rotation angle. The second actuator assembly selectively rotates the second tape head from the second base head rotation angle to a second adjusted head rotation angle. The controller independently controls the selective rotation of the first tape head and the second tape head based solely on servo information.

RELATED APPLICATIONS

This application is a Continuation Application and claims the benefitunder 35 U.S.C. 120 on U.S. patent application Ser. No. 17/078,760,filed on Oct. 23, 2020, and entitled “TOTAL DIMENSIONAL STABILITYCOMPENSATION SYSTEM AND METHOD FOR MAGNETIC TAPE DRIVE”. Additionally,U.S. patent application Ser. No. 17/078,760 claims priority from U.S.Provisional Application Ser. No. 62/927,001, filed on Oct. 28, 2019, andentitled “IMPROVED MAGNETIC TAPE MEDIA CARTRIDGE”. As far as permitted,the contents of U.S. patent application Ser. No. 17/078,760 and U.S.Provisional Application Ser. No. 62/927,001 are incorporated in theirentirety herein by reference.

BACKGROUND

Magnetic tape systems are configured for storing digital information, ordata, on magnetic tape. Magnetic tape cartridges are configured toretain and/or store magnetic tape that can be used in a magnetic tapedrive for purposes of reading data from and writing data to one or moredata tracks on the magnetic tape. During use of the magnetic tape drive,a tape head assembly of the magnetic tape drive is configured to be indirect contact with the magnetic tape from the magnetic tape cartridgeso that data can be written to and read from the magnetic tape as themagnetic tape moves across the tape head assembly at high speed.

In various applications, the magnetic tape utilizes a complex set ofpolymers containing a variety of materials exhibiting ferromagneticproperties. More particularly, a typical magnetic tape constructconsists of a main substrate material, comprised of Poly EtheneTerephthalate (PET), Polyethylene Naphthalate (PEN), Poly Aramid (PA),PIBO, or a variety of other potential viscoelastic materials.Subsequently, various layers of materials are prepared and coated,evaporated, sputtered, or otherwise “placed” onto the main substrate. Insuch applications, the backside of the main substrate can get a specialcoating that aids in guiding, packing, and transporting the magnetictape from one tape reel, e.g., a cartridge reel and/or a drive reel, toanother tape reel. The front side, or “Mag Side”, of the main substratemay receive multiple layers of materials, some of which may containlubricants and non-magnetic particles. In addition, an active magneticlayer on the front side may consist of either deposited (e.g., coated,evaporated or sputtered) magnetic coatings, with or without a magneticunderlayer, or a coated magnetic layer consisting of particulatematerials of many different types, such as MP particles (Fe₂O₃, orsimilar), Barium Ferrite, Iron Platinum, or other similar particlesystem.

A formatted magnetic tape of this type may include a set of two or moreservo bands (or servo tracks) that are usable to properly locate thetape head assembly, and a set of recorded data tracks that may bewritten in parallel numbering from only one or two, up to potentiallythousands. The data tracks are typically located between pairs of servobands. Hence, a typical tape head assembly would consist of one or moreservo readers, one or more data channels in parallel, and appropriatematerials to support the active elements across the width of themagnetic tape.

It is desired to increase the amount of data that can be read fromand/or written to any given magnetic tape. One way to increase theamount of data on a magnetic tape is to increase the areal density(product of linear density and track density) of the magnetic tape. Oneof the limiting factors to address the desire to achieve high orenhanced areal density is the sensitivity of the polymer stack (mainsubstrate, backside coatings, front side coatings) that makes up themagnetic tape to environmental conditions such as temperature, dynamictemperature, humidity, tension, cartridge creep and/or aging. Forexample, the Coefficient of Thermal Expansion (CTE) impacts the width ofthe magnetic tape as a function of temperature. In particular, the CTEis typically positive with the magnetic tape expanding as thetemperature increases. In a well-designed system, the designers striveto match the thermal expansion of the tape head assembly (approximately7.8 ppm for AlTiC Construction (Aluminum Titanium Carbide)) to themedia. As a “Steady State” condition, that can be achieved, howeverthere are dynamic thermal changes that occur that upset that balance.Similarly, the Coefficient of Hygroscopic Expansion (CHE) causes thewidth of the magnetic tape to change in the presence of humidity. TheCHE is typically positive as well with the magnetic tape expanding asthe humidity increases, although such is not always the case.Additionally, the width of the magnetic tape also changes as a functionof increasing or decreasing tension. The effects of tension aregenerally to change the width of tape as a function of increasing ordecreasing tension. Further, as the magnetic tape ages over time, thetension in the magnetic tape within the magnetic tape cartridge tends torelax, resulting in changes from its recorded condition.

At high areal densities, the read and write trackwidths can be smallerthan the dynamic changes due to Total Dimensional Stability (TDS)resulting from the effects of temperature, dynamic temperature,humidity, tension, cartridge creep and/or aging. When this happens, datawritten today may not be able to be read tomorrow.

One approach taken in the past is to limit the track density due to theneed for narrow tracks, continually reduce the CHE, CTE, tension, andaging characteristics such that a reasonable level of performance can beachieved over environment, tension and time. However, as track densitiesincrease, the effects become severe to the point the conventionalapproach cannot be successful.

Another approach is to reduce the read trackwidth to accommodate for thedimensional changes in the magnetic tape. However, as the trackdensities increase, the read trackwidths cannot always be reducedsufficiently to effectively accommodate such changes.

Accordingly, it is desired to find a more consistent and reliable systemand method to compensate for TDS resulting from environmental conditionssuch as temperature, dynamic temperature, humidity, tension, cartridgecreep and/or aging.

SUMMARY

The present invention is directed toward a tape drive for use with amagnetic tape including two spaced apart servo tracks and a first datatrack that is positioned substantially between the two servo tracksalong a length of the magnetic tape. In various embodiments, the tapedrive includes a first tape head, a first actuator assembly, a secondtape head, a second actuator assembly, and a controller. The first tapehead includes two spaced apart first servo elements that are eachconfigured to read one of the two servo tracks, and a first read/writeelement that is configured to one of read data from the first data trackand write data to the first data track. The first tape head ispositionable at a first base head rotation angle relative to transverseto the length of the magnetic tape. The first actuator assembly isconfigured to selectively rotate the first tape head relative to themagnetic tape from the first base head rotation angle to a firstadjusted head rotation angle that is different than the first base headrotation angle. The second tape head includes two spaced apart secondservo elements that are each configured to read one of the two servotracks, and a second read/write element that is configured to one ofread data from the first data track and write data to the first datatrack. The second tape head is positionable at a second base headrotation angle relative to transverse to the length of the magnetictape. The second actuator assembly is configured to selectively rotatethe second tape head relative to the magnetic tape from the second basehead rotation angle to a second adjusted head rotation angle that isdifferent than the second base head rotation angle. The controller (i)controls the first actuator assembly to selectively rotate the firsttape head relative to the magnetic tape from the first base headrotation angle to the first adjusted head rotation angle based solely onservo information from the two first servo elements reading the twoservo tracks; and (ii) controls the second actuator assembly toselectively rotate the second tape head relative to the magnetic tapefrom the second base head rotation angle to the second adjusted headrotation angle based solely on servo information from the two secondservo elements reading the two servo tracks, the controller controllingthe second actuator assembly independently of the first actuatorassembly.

In some embodiments, the controller (i) controls the first actuatorassembly to selectively rotate the first tape head relative to themagnetic tape from the first base head rotation angle to the firstadjusted head rotation angle based solely on timing-based servoinformation from the two first servo elements reading the two servotracks; and (ii) controls the second actuator assembly to selectivelyrotate the second tape head relative to the magnetic tape from thesecond base head rotation angle to the second adjusted head rotationangle based solely on timing-based servo information from the two secondservo elements reading the two servo tracks.

In certain embodiments, the magnetic tape includes a plurality of datatracks that are positioned substantially between the two spaced apartservo tracks along the length of the magnetic tape; the first tape headincludes a plurality of read/write elements that are each configured toone of read data from one of the plurality of data tracks and write datato one of the plurality of data tracks; and the second tape headincludes a plurality of read/write elements that are each configured toone of read data from one of the plurality of data tracks and write datato one of the plurality of data tracks.

In some embodiments, at least one of the first base head rotation angleand the second base head rotation angle is between approximately onedegree and 45 degrees relative to transverse to the length of themagnetic tape.

In certain embodiments, at least one of the first adjusted head rotationangle and the second adjusted head rotation angle is betweenapproximately zero degrees and 60 degrees relative to transverse to thelength of the magnetic tape.

In some embodiments, at least one of the first base head rotation angleand the second base head rotation angle is between approximately fivedegrees and 15 degrees relative to transverse to the length of themagnetic tape.

In certain embodiments, at least one of the first adjusted head rotationangle and the second adjusted head rotation angle is betweenapproximately zero degrees and 25 degrees relative to transverse to thelength of the magnetic tape.

In many embodiments, the two spaced apart servo tracks are spaced apartby a servo track spacing. In some embodiments, the first base headrotation angle is controlled by the controller so that each of the twospaced apart first servo elements are positioned to read one of the twospaced apart servo tracks that are spaced apart by the servo trackspacing; and the second base head rotation angle is controlled by thecontroller so that each of the two spaced apart second servo elementsare positioned to read one of the two spaced apart servo tracks that arespaced apart by the servo track spacing.

In certain embodiments, changes in environmental conditions cause achange in the servo track spacing to an adjusted servo track spacing. Insome embodiments, the first adjusted head rotation angle is controlledby the controller so that each of the two spaced apart first servoelements are positioned to read one of the two spaced apart servo tracksthat are spaced apart by the adjusted servo track spacing; and thesecond adjusted head rotation angle is controlled by the controller sothat each of the two spaced apart second servo elements are positionedto read one of the two spaced apart servo tracks that are spaced apartby the adjusted servo track spacing.

In certain embodiments, the first tape head includes a center of mass;and the first actuator assembly is configured to rotate the first tapehead relative to the magnetic tape about a first pivot point that ispositioned at the center of mass of the first tape head.

In some embodiments, the second tape head includes a center of mass; andthe second actuator assembly is configured to rotate the second tapehead relative to the magnetic tape about a second pivot point that ispositioned at the center of mass of the second tape head.

In many embodiments, the first actuator assembly is further configuredto move the first tape head transversely relative to the magnetic tape;and the second actuator assembly is further configured to move thesecond tape head transversely relative to the magnetic tape.

The present invention is also directed toward a tape drive for use witha magnetic tape including two spaced apart servo tracks and a first datatrack that are positioned along a length of the magnetic tape, the tapedrive including (A) a tape head assembly including (i) at least twoservo elements that are each configured to read one of the two servotracks, (ii) a first read/write element that is configured to one ofread data from the first data track and write data to the first datatrack, the first read/write element being positionable at a first baserotation angle relative to transverse to the length of the magnetictape, and (iii) a second read/write element that is configured to one ofread data from the first data track and write data to the first datatrack, the second read/write element being positionable at a second baserotation angle relative to transverse to the length of the magnetictape; (B) an actuator assembly that is configured to (i) selectivelyrotate the first read/write element relative to the magnetic tape fromthe first base rotation angle to a first adjusted rotation angle that isdifferent than the first base rotation angle, and (ii) selectivelyrotate the second read/write element relative to the magnetic tape fromthe second base rotation angle to a second adjusted rotation angle thatis different than the second base rotation angle; and (C) a controllerthat controls the actuator assembly to selectively and independently (i)rotate the first read/write element relative to the magnetic tape fromthe first base rotation angle to the first adjusted rotation angle basedsolely on servo information from the at least two servo elements readingthe two servo tracks, and (ii) rotate the second read/write elementrelative to the magnetic tape from the second base rotation angle to thesecond adjusted rotation angle based solely on servo information fromthe at least two servo elements reading the two servo tracks.

The present invention is further directed toward a tape drive for usewith a magnetic tape including two spaced apart servo tracks that arespaced apart by a servo track spacing and a plurality of data tracksthat are positioned substantially between the two servo tracks along alength of the magnetic tape, the tape drive including (A) a first tapehead including two spaced apart first servo elements that are eachconfigured to read one of the two servo tracks, and a plurality of firstread/write elements that are each configured to one of read data fromone of the plurality of data tracks and write data to one of theplurality of data tracks, the first tape head being positionable at afirst base head rotation angle of between approximately one degree and45 degrees relative to transverse to the length of the magnetic tape;(B) a first actuator assembly that is configured to selectively rotatethe first tape head relative to the magnetic tape from the first basehead rotation angle to a first adjusted head rotation angle that isdifferent than the first base head rotation angle, the first adjustedhead rotation angle being between approximately zero degrees and 60degrees relative to transverse to the length of the magnetic tape; (C) asecond tape head including two spaced apart second servo elements thatare each configured to read one of the two servo tracks, and a pluralityof second read/write elements that are each configured to one of readdata from one of the plurality of data tracks and write data to one ofthe plurality of data tracks, the second tape head being positionable ata second base head rotation angle of between approximately one degreeand 45 degrees relative to transverse to the length of the magnetictape; (D) a second actuator assembly that is configured to selectivelyrotate the second tape head relative to the magnetic tape from thesecond base head rotation angle to a second adjusted head rotation anglethat is different than the second base head rotation angle, the secondadjusted head rotation angle being between approximately zero degreesand 60 degrees relative to transverse to the length of the magnetictape; and (E) a controller that selectively and independently (i)controls the first actuator assembly to selectively rotate the firsttape head relative to the magnetic tape from the first base headrotation angle to the first adjusted head rotation angle based solely onservo information from the two first servo elements reading the twoservo tracks; and (ii) controls the second actuator assembly toselectively rotate the second tape head relative to the magnetic tapefrom the second base head rotation angle to the second adjusted headrotation angle based solely on servo information from the two secondservo elements reading the two servo tracks; wherein the first base headrotation angle is controlled by the controller so that each of the twospaced apart first servo elements are positioned to read one of the twospaced apart servo tracks that are spaced apart by the servo trackspacing; wherein the second base head rotation angle is controlled bythe controller so that each of the two spaced apart second servoelements are positioned to read one of the two spaced apart servo tracksthat are spaced apart by the servo track spacing; wherein changes inenvironment conditions cause a change in the servo track spacing to anadjusted servo track spacing; wherein the first adjusted head rotationangle is controlled by the controller so that each of the two spacedapart first servo elements are positioned to read one of the two spacedapart servo tracks that are spaced apart by the adjusted servo trackspacing; and wherein the second adjusted head rotation angle iscontrolled by the controller so that each of the two spaced apart secondservo elements are positioned to read one of the two spaced apart servotracks that are spaced apart by the adjusted servo track spacing.

This summary is an overview of some of the teachings of the presentapplication and is not intended to be an exclusive or exhaustivetreatment of the present subject matter. Further details are found inthe detailed description and appended claims. Other aspects will beapparent to persons skilled in the art upon reading and understandingthe following detailed description and viewing the drawings that form apart thereof, each of which is not to be taken in a limiting sense. Thescope herein is defined by the appended claims and their legalequivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself,both as to its structure and its operation, will be best understood fromthe accompanying drawings, taken in conjunction with the accompanyingdescription, in which similar reference characters refer to similarparts, and in which:

FIG. 1 is a simplified schematic top view illustration of a magnetictape system including an embodiment of a magnetic tape drive havingfeatures of the present invention, and a magnetic tape cartridge thathas been inserted into the magnetic tape drive;

FIG. 2 is a simplified schematic illustration of a portion of a magnetictape that can be retained within the magnetic tape cartridge, and anembodiment of a tape head assembly having features of the presentinvention that can form part of the magnetic tape drive for purposes ofreading data from and writing data to the magnetic tape;

FIG. 3A is a simplified schematic illustration of a portion of themagnetic tape, and another embodiment of the tape head assemblyincluding a plurality of tape heads being shown in a first position; and

FIG. 3B is a simplified schematic illustration of the portion of themagnetic tape and the tape head assembly illustrated in FIG. 3A, theplurality of tape heads being shown in a second position.

While embodiments of the present invention are susceptible to variousmodifications and alternative forms, specifics thereof have been shownby way of example and drawings, and are described in detail herein. Itis understood, however, that the scope herein is not limited to theparticular embodiments described. On the contrary, the intention is tocover modifications, equivalents, and alternatives falling within thespirit and scope herein.

DESCRIPTION

Embodiments of the present invention are described herein in the contextof a total dimension stability (TDS) compensation system and method fora magnetic tape drive that controls a position and/or orientation of atape head assembly such that read/write elements of the tape headassembly can more accurately read data from and/or write data to one ormore data tracks on a magnetic tape. More particularly, during use of amagnetic tape system, the position and/or orientation of the tape headassembly of the magnetic tape drive can be selectively adjusted andcontrolled to compensate for changes in environmental conditions thatmay impact the width of the magnetic tape and the position and/orspacing of servo tracks on the magnetic tape. Thus, the TDS compensationsystem and method is able to compensate for changes in position and/orspacing of the one or more data tracks on the magnetic tape due tochanges in environmental conditions such as temperature, dynamictemperature, humidity, tension, cartridge creep and/or aging.

Those of ordinary skill in the art will realize that the followingdetailed description of the present invention is illustrative only andis not intended to be in any way limiting. Other embodiments of thepresent invention will readily suggest themselves to such skilledpersons having the benefit of this disclosure. Reference will now bemade in detail to implementations of the present invention asillustrated in the accompanying drawings. The same or similarnomenclature and/or reference indicators will be used throughout thedrawings and the following detailed description to refer to the same orlike parts.

In the interest of clarity, not all of the routine features of theimplementations described herein are shown and described. It will, ofcourse, be appreciated that in the development of any such actualimplementation, numerous implementation-specific decisions must be madein order to achieve the developer's specific goals, such as compliancewith application-related and business-related constraints, and thatthese specific goals will vary from one implementation to another andfrom one developer to another. Moreover, it is appreciated that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skill in the art having the benefit of this disclosure.

FIG. 1 is a simplified schematic top view illustration of a magnetictape system 10 (also referred to herein simply as a “tape system”)including an embodiment of a magnetic tape drive 12 (also referred toherein simply as a “tape drive”) having features of the presentinvention, and a magnetic tape cartridge 14 (also referred to hereinsimply as a “tape cartridge”) that has been inserted into the tape drive12. It is appreciated that in many aspects the tape drive 12 as shown inFIG. 1 represents a generic tape drive, and in such aspects is shown byway of example and not by way of limitation. In some embodiments, thetape drive 12 operates in compliance with an LTO specification, such asLTO-6, LTO-7, LTO-8 or LTO-9. Stated in another manner, in suchembodiments, the tape cartridge 14 is an LTO-compatible tape cartridge.However, it is appreciated that the technology described herein can beapplied to any serpentine-style embodiment.

During use of the tape system 10, the tape cartridge 14 is inserted intothe tape drive 12 to read data from and/or write data to a magnetic tape16 that is retained within the tape cartridge 14. As shown, the tapecartridge 14 includes a cartridge reel 18 that includes and/or defines acartridge hub 20. The magnetic tape 16 is spooled about the cartridgehub 20 of the cartridge reel 18. In certain embodiments, the magnetictape 16 can include at least one servo track 222 (illustrated in FIG. 2) and a plurality of data tracks 224 (illustrated in FIG. 2 ) that runalong a longitudinal length of the magnetic tape 16. In one suchembodiment, the magnetic tape 16 can include two servo tracks 222 thatare positioned near opposing outer edges of the magnetic tape 16 along alength of the magnetic tape 16, and the plurality of data tracks 224 canbe positioned along the magnetic tape 16 substantially between the twoservo tracks 222. Additionally, in such embodiments, each of the servotracks 222 and data tracks 224 can be positioned substantially parallelto each other.

It is appreciated that the at least one servo track 222, which caninclude any suitable or desired number of servo tracks withoutlimitation, can also be referred to as a “first servo track”, a “secondservo track”, etc. Additionally, it is further appreciated that theplurality of data tracks 224, which can include any suitable or desirednumber of data tracks without limitation, can also be referred to as a“first data track”, a “second data track”, etc.

The tape cartridge 14 supplies the magnetic tape 16 to the tape drive12. More particularly, when the tape cartridge 14 is inserted into thetape drive 12, one end of the magnetic tape 16 is taken up within thetape drive 12 to be wrapped around a drive reel 26 included in the tapedrive 12. The magnetic tape 16 traverses a predefined path between thecartridge reel 18 and the drive reel 26, which is defined, a least inpart, by one or more rollers 28 (two are shown in FIG. 1 ) positioned atstrategic positions along the predefined path. The rollers 28 may alsoaid in limiting gross lateral movement (i.e. in and out of the page asshown in FIG. 1 ) of the magnetic tape 16, i.e. lateral tape motion or“LTM”.

Along the predefined path, the drive reel 26 moves the magnetic tape 16across a tape head assembly 30 (also sometimes referred to herein simplyas a “head assembly”). In certain embodiments, the head assembly 30includes a plurality of read/write elements 232 (illustrated in FIG. 2 )that are configured to read data from and/or write data to the magnetictape 16. In particular, the head assembly 30 is positioned in closeproximity to the predefined path of the magnetic tape 16 such that asthe magnetic tape 16 travels in the longitudinal direction (by beingwound from the cartridge reel 18 to the drive reel 26 or vice versa) thehead assembly 30 and/or the read/write elements 232 can read data fromand/or write data to a particular data track 224 at a longitudinalposition of the magnetic tape 16. Additionally, in some embodiments, thehead assembly 30 can include one or more servo elements 234 (illustratedin FIG. 2 ) configured to read the servo track(s) 222 of the magnetictape 16. The servo elements 234 reading of the servo tracks 222 isutilized to ensure the proper positioning of the head assembly 30relative to the magnetic tape 16, e.g., so that the read/write elements232 can be properly and accurately aligned with the data tracks 224.

In alternative embodiments, it is appreciated that the head assembly 30can include one or more individual tape heads (or “bumps”), with eachtape head including one or more servo elements 234 (and preferably atleast two servo elements 234), and at least one read/write element 232(and preferably a plurality of read/write elements 232). In onenon-exclusive such embodiment, the head assembly 30 can include a singletape head that includes a pair of servo elements 234 and a plurality ofread/write elements 232 that are positioned substantially between theservo elements 234. Alternatively, in another embodiment, the headassembly 30 can include more than one tape head. For example, in certainsuch alternative embodiments, the head assembly 30 can include two,three, four or five individual tape heads. Further, in certain suchalternative embodiments, in addition to each individual tape headincluding at least one, and preferably two servo elements 234, suchindividual tape heads can be dedicated for purposes of either readingdata from the data tracks 224 on the magnetic tape 16 (i.e. as a readhead including only read elements and no write elements), or writingdata to the data tracks 224 on the magnetic tape 16 (i.e. as a writehead including only write elements and no read elements). Stillalternatively, each individual tape head can include both read elementsand write elements.

It is appreciated that the one or more servo elements 234 can also bereferred to as a “first servo element”, a “second servo element”, etc.Additionally, it is further appreciated that the at least one read/writeelement 232 can also be referred to as a “first read/write element”, a“second read/write element”, etc.

In some embodiments, as shown, the tape drive 12 can also include acartridge reel motor 36 (illustrated as a box in phantom) that generatesthe necessary force to rotate the cartridge reel 18 at will, and acartridge reel encoder 38, e.g., a sensor or detector, that isconfigured to output signals representing the pulse rate (or rotationrate) of the cartridge reel motor 36. Additionally, the tape drive 12can further include a drive reel motor 40 (illustrated as a box inphantom) that generates the necessary force to rotate the drive reel 26at will, and a drive reel encoder 42, e.g., a sensor or detector, thatis configured to output signals representing the pulse rate (or rotationrate) of the drive reel motor 40.

As an overview, as illustrated in this embodiment, the tape drive 12further includes an actuator assembly 44 including one or moreactuators, and a controller 46, including one or more processors andcircuits, that can be communicatively coupled to the head assembly 30.In various embodiments, and as described in greater detail herein below,the actuator assembly 44 is configured to move the head assembly 30under control of the controller 46 in order to control a transverseposition and/or a rotational position of the head assembly 30 relativeto the magnetic tape 16 based on a signal provided by the controller 46.As such, the actuator assembly 44 comprises a mechanical positioner tomove the head assembly 30 up or down transversely and/or rotationallyrelative to the magnetic tape 16 so that the head assembly 30 is bestpositioned to enable the read/write elements 232 to accurately read datafrom and/or write data to particular data tracks 224. More particularly,the actuator assembly 44 is configured to move the head assembly 30under control of the controller 46 based on servo information feedbackregarding the positions of the servo elements 234 relative to the servotracks 222. Subsequently, the actuator assembly 44 moves the headassembly 30 transversely and/or rotationally so that the servo elements234 are accurately aligned with the servo tracks 222, and thus theread/write elements 232 can be accurately aligned with the data tracks224. Thus, by controlling the transverse and/or rotational position ofthe head assembly 30 relative to the magnetic tape 16, a particular datatrack 224 of the magnetic tape 16 can be accessed by a correspondingread/write element 232 as desired. It is appreciated that in certainembodiments, the actuator assembly 44 can include separate actuators forpurposes of moving the head assembly 30 transversely relative to themagnetic tape 16 and for purposes of moving the head assembly 30rotationally relative to the magnetic tape 16.

Additionally, it is appreciated that the relative positions of the servotracks 222 and the data tracks 224, and/or a spacing between the tracks222, 224 can be impacted by various environmental conditions to whichthe magnetic tape 16 may be subjected during the life of the magnetictape 16. More specifically, environmental conditions such astemperature, dynamic temperature, humidity, tension, cartridge creepand/or aging can impact a width of the magnetic tape 16, and thus impactthe relative positions of and/or spacing between the tracks 222, 224.Accordingly, as such environmental conditions cause dynamic changes tothe positions and spacing of the tracks 222, 224 along the magnetic tape16 due to Total Dimensional Stability (TDS), the controller 46 canreceive feedback based on servo information, i.e. the accuracy of thepositions of the servo elements 234 relative to the servo tracks 222,and use such feedback to control the actuator assembly 44 to move and/orposition the head assembly 30 as desired.

In embodiments of the head assembly 30 that include more than oneindividual head, a separate actuator assembly 44 and controller 46 canbe provided for each individual head, or the head assembly 30 canutilize a single actuator assembly 44 to selectively move one or moreheads and/or a single controller 46 to selectively control one or moreheads.

It is appreciated that the actuator assembly 44 can have any suitabledesign for purposes of moving the head assembly 30 as necessary toensure that the read/write elements 232 can be accurately aligned withthe data tracks 224 such that data can be effectively read from and/orwritten to the data tracks 224 on the magnetic tape 16. For example, incertain embodiments, the actuator assembly 44 can include apiezoelectric actuator, a micro electro-mechanical systems (MEMS)actuator, a servo tilt actuator, and/or another suitable type ofactuator.

It is further appreciated that, in addition to the controller 46 beingin communication with the actuator assembly 44, the controller 46 canalso be in communication with a number of other components within thetape drive 12. For example, although not specifically shown in FIG. 1 ,each of the cartridge reel motor 36, the cartridge reel encoder 38, thedrive reel motor 40, and the drive reel encoder 42 can be incommunication with the controller 46. As such, the controller 46 can beconfigured to perform various specified operations, either individually,or in combination with other software, hardware and/or firmwareelements.

FIG. 1 also illustrates that, in some embodiments, the tape cartridge 14further includes a cartridge reel alignment assembly 48 for the magnetictape 16 such that the magnetic tape 16 is kept in a desired lateralposition (i.e. with limited lateral movement) as it is wound (andunwound) around the cartridge hub 20. Thus, the cartridge reel alignmentassembly 48 can be helpful for higher track density applications. It isappreciated that in certain embodiments, the cartridge reel alignmentassembly 48 can also be configured to minimize air entrainment that mayotherwise occur during the winding and unwinding of the magnetic tape 16around the cartridge hub 16.

Additionally, in some embodiments, as shown in FIG. 1 , the tape drive12 can also be modified to include a drive reel alignment assembly 50for the magnetic tape 16 such that the magnetic tape 16 is kept in adesired lateral position as it is wound (and unwound) around the drivereel 26. It is appreciated that in certain embodiments, the drive reelalignment assembly 50 can also be configured to minimize air entrainmentthat may otherwise occur during the winding and unwinding of themagnetic tape 16 around the drive reel 26. It is further appreciatedthat the general design and functioning of the drive reel alignmentassembly 50 can be substantially similar to that of the cartridge reelalignment assembly 48.

FIG. 2 is a simplified schematic illustration of a portion of a magnetictape 216 that can be retained within the magnetic tape cartridge 14(illustrated in FIG. 1 ), and an embodiment of a tape head assembly 230having features of the present invention that can form part of themagnetic tape drive 12 (illustrated in FIG. 1 ) for purposes of readingdata from and writing data to the magnetic tape 216.

As illustrated, the magnetic tape 216 includes one or more servo tracks222 and one or more data tracks 224 (illustrated with a series of “X”sand “O”s). In one embodiment, as shown, the magnetic tape 216 includestwo spaced apart servo tracks 222 that are positioned near opposinglateral tape edges 216E of the magnetic tape 216. However, it isappreciated that the magnetic tape 216 can include any suitable numberof servo tracks 222, and the servo tracks 222 can be positioned in anysuitable manner relative to a tape width 252 of the magnetic tape 216.More particularly, in alternative embodiments, the magnetic tape 216 caninclude greater than two servo tracks 222 or only a single servo track222.

It is further appreciated that the magnetic tape 216 can include anysuitable number of data tracks 224. More particularly, although FIG. 2illustrates the magnetic tape 216 as including four data tracks 224,this is merely for purposes of simplicity and ease of illustration, andit is appreciated that the magnetic tape 216 can alternatively includegreater than four data tracks 224 or fewer than four data tracks 224.For example, in various alternative embodiments, the magnetic tape 216can include only one data track 224 up to potentially thousands of datatracks 224. In one such non-exclusive alternative embodiment, themagnetic tape 216 can be configured to include 32 individual data tracks224.

Additionally, as shown, in certain embodiments, the data tracks 224 canbe positioned substantially between the servo tracks 222 along a tapelength 216L (or longitudinal direction, shown as a two-headed arrow) ofthe magnetic tape 216. Moreover, as illustrated in FIG. 2 , the datatracks 224 can be spaced apart and substantially parallel to each otherand the servo tracks 222.

The head assembly 230 can include any desired number of tape heads 254.In the embodiment shown in FIG. 2 , the head assembly 230 includes onetape head 254. Alternatively, the head assembly 230 can include greaterthan one tape head 254. For example, in certain non-exclusivealternative embodiments, the head assembly 230 can include two, three,four or five individual tape heads 254.

As illustrated in this embodiment, the tape head 254 and/or the headassembly 230 includes one or more servo elements 234 that are utilizedto read the servo track(s) 222 to ensure the proper positioning of thehead assembly 230 relative to the magnetic tape 216, and one or moreread/write elements 232. In one embodiment, as shown, the tape head 254includes two spaced apart servo elements 234 that are positioned nearopposing ends, e.g., near a top and a bottom, of the tape head 254.Alternatively, the tape head 254 can include greater than two servoelements 234 or only a single servo element 234. Still alternatively,the servo elements 234 can be positioned in a different manner than isshown in FIG. 2 . It is appreciated that the servo elements 234 arepositioned in a manner to effectively correspond with the servo tracks222 on the magnetic tape 216.

The tape head 254 can include any suitable number of read/write elements232 that are configured to read data from and/or write data to the datatracks 224 on the magnetic tape 216. More particularly, although FIG. 2illustrates the tape head 254 as including four read/write elements 232,it is appreciated that the tape head 254 can alternatively includegreater than four read/write elements 232 or fewer than four read/writeelements 232. In one such non-exclusive alternative embodiment, the tapehead 254 can be configured to include 32 individual read/write elements232. It is appreciated that the number of read/write elements 232 willtypically be the same as the number of data tracks 224 on the magnetictape 216, such that each read/write element 232 is configured to readdata from and/or write data to one of the data tracks 224.

It is appreciated that the ability of the read/write elements 232 toeffectively read data from and/or write data to the data tracks 224 isdependent on the proper and accurate positioning of the read/writeelements 232 relative to the data tracks 224. This is determined basedon the proper positioning of the servo elements 234 relative to theservo tracks 222. As noted above, changes in environmental conditionscan cause corresponding changes to the tape width 252 of the magnetictape 216. For example, certain changes in environmental conditions canincrease the tape width 252 of the magnetic tape 216, thereby moving theservo tracks 222 farther apart. Similarly, in such situations, the datatracks 224 are moved farther apart as well. Without the ability to adaptto such environmental changes, as in previous tape drives, if the changein environment is too severe, the data tracks 224 become unreadable.Worse than that, damage can occur to previously written data tracks 224if new data tracks 224 are written next to the old data tracks 224 undera radically different environment. Moreover, as track densitiesincrease, the read and write trackwidths of the data tracks 224 arereduced significantly. This makes the data tracks 224 more sensitive tothe environment. Fundamentally, if the tape head 254 is positionedperpendicular to the tape edges 216E of the magnetic tape 216, as isdone in most traditional tape drives, nothing can be done to compensatefor any environmental conditions that increase the tape width 252 of themagnetic tape 216.

Importantly, in various embodiments illustrated and described herein, inorder to enable the tape head 254 to adapt to potential changes in tapewidth 252 due to changes in environmental conditions such astemperature, dynamic temperature, humidity, tension, cartridge creepand/or aging, as shown, the tape head 254 can be initially oriented at abase head rotation angle 256 (illustrated with the tape head 254 shownin solid lines) relative to transverse (or perpendicular) to the length216L (or longitudinal direction) of the magnetic tape 216. In certainnon-excusive alternative embodiments, the tape head 254 can be initiallyoriented with a base head rotation angle 256 of greater than zerodegrees, such as between approximately one degree and 45 degreesrelative to transverse to the length 216L of the magnetic tape 216. Moreparticularly, in some such embodiments, the tape head 254 can beinitially oriented with a base head rotation angle 256 of betweenapproximately two degrees and 45 degrees, five degrees and 40 degrees,five degrees and 35 degrees, five degrees and 30 degrees, five degreesand 25 degrees, five degrees and 20 degrees, five degrees and 15degrees, or five degrees and ten degrees relative to transverse to thelength 216L of the magnetic tape 216. It is appreciated that the basehead rotation angle 256 should be set such that the one or more servoelements 234 are initially effectively aligned with the one or moreservo tracks 222 on the magnetic tape 216, and the one or moreread/write elements 232 are effectively aligned with the one or moredata tracks 224 on the magnetic tape 216, prior to and/or at the startof use of the tape system 10 (illustrated in FIG. 1 ). Alternatively, inanother embodiment, the tape head 254 can be initially oriented withanother suitable base head rotation angle 256 relative to transverse tothe length 216L of the magnetic tape 216. It is further appreciated thatin certain embodiments, the tape head 254 can be initially oriented withthe base head rotation angle 256 equal to zero degrees relative totransverse to the length 216L of the magnetic tape 216, but such initialorientation may impact the ability of the tape system 10 (illustrated inFIG. 1 ) to effectively react to certain changes in environmentalconditions and/or certain changes in dimension of the magnetic tape 216.

During use of the tape system 10, as noted, the magnetic tape 216 willbe subjected to potential changes in environmental conditions, e.g.,changes in one or more of temperature, dynamic temperature, humidity,tension, cartridge creep and/or aging, which can impact the tape width252 of the magnetic tape 216. Additionally, it is appreciated that anysuch changes to the tape width 252 of the magnetic tape 216 will causecorresponding changes to a servo track spacing 258 between the servotracks 222 on the magnetic tape 216, i.e. the servo tracks 222 will movefrom the servo track spacing 258 to an adjusted servo track spacing. Forexample, increases in temperature and/or humidity will typically causean increase in the tape width 252 of the magnetic tape 216, and thus anincrease in the servo track spacing 258 to the adjusted servo trackspacing between the servo tracks 222 on the magnetic tape 216.Additionally, the effects of tension are generally to reduce the tapewidth 252 of the magnetic tape 216, and thus reduce the servo trackspacing 258 to the adjusted servo track spacing between the servo tracks222 on the magnetic tape 216, as a function of increasing tension.

In order to determine the changes in servo track spacing 258 between theservo tracks 222 on the magnetic tape 216 over time, any potentialposition error of the servo elements 234 relative to the servo tracks222 can be determined at any time. In particular, the amount ofcompensation (or change) can be determined by averaging the positionerror of each of the servo elements 234 to zero by tilting or rotatingthe tape head 254 relative to the base head rotation angle 256. Statedin another manner, if the tape width 252 of the magnetic tape 216changes due to any environmental conditions such as temperature, dynamictemperature, humidity, tension, cartridge creep and/or aging, therotation and/or orientation (or tilt) of the tape head 254 relative totransverse to the length 216L of the magnetic tape 216 can beindependently servoed to compensate for any such changes. Thus, theactuator assembly 44, under control of the controller 46, can move thehead assembly 230 and/or the tape head 254 rotationally so that theservo elements 234 are again accurately aligned with the servo tracks222, and thus the read/write elements 232 can again be accuratelyaligned with the data tracks 224. As such, in various embodiments, thecontroller 46 is used to control the actuator assembly 44 to control arotational position of the head assembly 230 and/or the tape head 254relative to the magnetic tape 216 based solely on servo informationfeedback.

More specifically, if it is determined that the tape width 252 of themagnetic tape 216, and thus the servo track spacing 258 between theservo tracks 222 on the magnetic tape 216, has increased, then thecontroller 46 (illustrated in FIG. 1 ) can control the actuator assembly44 (illustrated in FIG. 1 ) to rotate the tape head 254 so that the tapehead 254 is oriented at an adjusted head rotation angle 260 (illustratedwith the tape head 254 shown in dashed lines) relative to transverse tothe length 216L of the magnetic tape 216 that is different than, i.e.less than, the base head rotation angle 256. Additionally or in thealternative, if it is determined that the tape width 252 of the magnetictape 216, and thus the servo track spacing 258 between the servo tracks222 on the magnetic tape 216, has decreased, then the controller 46 cancontrol the actuator assembly 44 to rotate the tape head 254 so that thetape head 254 is oriented at an adjusted head rotation angle 260relative to transverse to the length 216L of the magnetic tape 216 thatis different than, i.e. greater than, the base head rotation angle 256.Thus, it is appreciated that the adjusted head rotation angle 260relative to transverse to the length 216L of the magnetic tape 216, asadjusted based on feedback from servo information due to changes inenvironmental conditions, can be greater than or less than the base headrotation angle 256. For example, in certain non-exclusive alternativeembodiments, the adjusted head rotation angle 260 can be betweenapproximately zero degrees and 60 degrees relative to transverse to thelength 216L of the magnetic tape 216. More particularly, in some suchembodiments, the tape head 254 can be adjusted rotationally to anadjusted head rotation angle 260 of between approximately zero degreesand 25 degrees relative to transverse to the length 216L of the magnetictape 216. Alternatively, the tape head 254 can be adjusted rotationallyto an adjusted head rotation angle 260 of another suitable anglerelative to transverse to the length 216L of the magnetic tape 216.

Additionally, in various embodiments, the tape head 254 is movableand/or rotatable with the actuator assembly 44 relative to the magnetictape 216 by between approximately one degree and 45 degrees from thebase head rotation angle 256 to the adjusted head rotation angle 260.More particularly, in certain such non-exclusive embodiments, the tapehead 254 is movable and/or rotatable with the actuator assembly 44 by atleast approximately one degree, two degrees, three degrees, fivedegrees, seven degrees, ten degrees, 12 degrees, 15 degrees, 20 degrees,25 degrees, 30 degrees, 35 degrees, 40 degrees, or 45 degrees from thebase head rotation angle 256 to the adjusted head rotation angle 260.Alternatively, the tape head 254 is movable and/or rotatable with theactuator assembly 44 by another suitable number of degrees from the basehead rotation angle 256 to the adjusted head rotation angle 260.

In certain embodiments, as illustrated herein, the tape head 254 can beconfigured to rotate about a center of mass of the tape head 254. Moreparticularly, in this embodiment, the tape head 254 can be rotated bythe actuator assembly 44, under control of the controller 46, about apivot point 262 that is positioned at the center of mass of the tapehead 254. Alternatively, in other embodiments, the tape head 254 can beconfigured to rotate about other portions of the tape head 254. Forexample, in certain such embodiments, the tape head 254 can beconfigured to rotate about a centerline of one of the servo elements234, e.g., either the top servo element 234 or the bottom servo element234 shown in FIG. 2 .

It is appreciated that by positioning and rotating the tape head 254 asdescribed, the need for adjacent track write elements and read elementsis no longer a necessity for future high areal density systems. The keylimiting factor to achieving high areal density performance issignificant increases in track density. With the embodiments illustratedand described herein, dimensional stability is no longer aconsideration, and expensive substrate materials are no longer required.More particularly, any substrate material can be used for multi-trackrecording that suffers from dimensional stability concerns. Furthermore,a width of the read/write elements 232 no longer has to be severelylimited to accommodate environmental conditions, thereby allowing thewidth of the read/write elements 232 to be approximately equal to trackpitch of the data tracks 224.

It is further appreciated that the layout of the read/write elements 232and the servo elements 234 on the tape head 254 changes slightly due tothe rotation and/or positioning of the tape head 254 relative to themagnetic tape 216. In particular, the distance or spacing between theread/write elements 232 and the servo elements 234 can increase slightlydue to the required compensation for TDS in situations where changes inenvironmental conditions cause increases in the tape width 252 of themagnetic tape 216. As an example, assume the servo track spacing 258 istypically approximately 3000 microns. In addition, assume that theworst-case TDS over all environments, due to noted environmental changesis 2 microns. Thus, the maximum new servo element spacing would be the3000 microns+2 microns due to compensation for TDS. The read/writeelements 232 would be spread apart similarly. As an example, assume thetrack spacing would normally be 43 microns. Further assume that the tapehead 254 includes 32 read/write elements 232 (any number greater thanone is acceptable). The distance the read/write elements 232 would bespread apart would be the normal 43 microns+2 microns/32. However, it isappreciated that the spacing between servo elements 234 and the spacingbetween read/write elements 232 need not be based solely only thepotential compensation for TDS. Rather, such spacing can be larger ifdesired. In fact, tilt servo gain would increase for larger spacingdistances.

FIG. 3A is a simplified schematic illustration of a portion of themagnetic tape 316, and another embodiment of the tape head assembly 330that can form part of the magnetic tape drive 12 (illustrated in FIG. 1) for purposes of reading data from and/or writing data to the magnetictape 316.

The magnetic tape 316 can be substantially similar to the magnetic tapeillustrated and described herein above. For example, the magnetic tape316 again includes one or more servo tracks 322 (and again preferably atleast two servo tracks 322) and one or more data tracks 324 (illustratedwith a series of “X”s and “O”s). More particularly, in one embodiment,the magnetic tape 316 again includes two spaced apart servo tracks 322that can be positioned near opposing lateral tape edges 316E of themagnetic tape 316. Additionally, the magnetic tape 316 again includesany suitable number of data tracks 324. Although FIG. 3A illustrates themagnetic tape 316 as including four data tracks 324, this is merely forpurposes of simplicity and ease of illustration, and it is appreciatedthat the magnetic tape 316 can alternatively include greater than fourdata tracks 324 or fewer than four data tracks 324. Further, as shown,in certain embodiments, the data tracks 324 can again be positionedsubstantially between the servo tracks 322, and can be spaced apart andsubstantially parallel to each other and the servo tracks 322.

As shown in FIG. 3A, in this embodiment, the head assembly 330 issomewhat different than in the previous embodiments. More specifically,in the embodiment illustrated in FIG. 3A, the head assembly 330 includesthree individual tape heads (or bumps), i.e. a first tape head 354A, asecond tape head 354B, and a third tape head 354C. Similar to theprevious embodiments, each tape head 354A, 354B, 354C can include one ormore servo elements 334 (and preferably at least two servo elements334), and at least one read/write element 332 (and preferably aplurality of read/write elements 332). In one non-exclusive suchembodiment, each tape head 354A, 354B, 354C includes a pair of servoelements 334 that are utilized to read the servo track(s) 322 to ensurethe proper positioning of the head assembly 330 relative to the magnetictape 316, and a plurality of read/write elements 332 that are positionedsubstantially between the servo elements 334. Additionally, in someembodiments, each individual tape head 354A, 354B, 354C can be dedicatedfor purposes of either reading data from the data tracks 324 on themagnetic tape 316 (i.e. as a read head including only read elements andno write elements), or writing data to the data tracks 324 on themagnetic tape 316 (i.e. as a write head including only write elementsand no read elements). Alternatively, each individual tape head 354A,354B, 354C can include both read elements and write elements. Stillalternatively, one or more of the individual tape heads 354A, 354B, 354Ccan be designed without any servo elements, and the servo elements 334of any one tape head 354A, 354B, 354C can be utilized in the process ofcollectively controlling the position and/or orientation of more thanone tape head 354A, 354B, 354C.

Each tape head 354A, 354B, 354C can include any suitable number ofread/write elements 332 that are configured to read data from and/orwrite data to the data tracks 324 on the magnetic tape 316. Moreparticularly, although FIG. 3A illustrates each tape head 354A, 354B,354C as including four read/write elements 332, it is appreciated thateach tape head 354A, 354B, 354C can alternatively include greater thanfour read/write elements 332 or fewer than four read/write elements 332.It is appreciated that the number of read/write elements 332 for eachtape head 354A, 354B, 354C will typically be the same as the number ofdata tracks 324 on the magnetic tape 316, such that each read/writeelement 332 is configured to read data from and/or write data to one ofthe data tracks 324.

The ability of the read/write elements 332 to effectively read data fromand/or write data to the data tracks 324 is dependent on the proper andaccurate positioning of the read/write elements 332 relative to the datatracks 324. This is again determined based on the proper positioning ofthe servo elements 334 relative to the servo tracks 322. In thisembodiment, it is again appreciated that the relative positions of theservo tracks 322 and the data tracks 324, and/or a spacing between thetracks 322, 324 can be impacted by various environmental conditions,i.e. temperature, dynamic temperature, humidity, tension, cartridgecreep and/or aging, to which the magnetic tape 316 may be subjectedduring the life of the magnetic tape 316. More specifically,environmental conditions such as temperature, dynamic temperature,humidity, tension, cartridge creep and/or aging can impact a tape width352 of the magnetic tape 316, and thus impact the relative positions ofand/or spacing between the tracks 322, 324. Accordingly, as suchenvironmental conditions cause dynamic changes to the positions andspacing of the tracks 322, 324 along the magnetic tape 316 due to TotalDimensional Stability (TDS), the controller 46 (illustrated in FIG. 1 )can again receive feedback based on servo information, i.e. the accuracyof the positions of the servo elements 334 relative to the servo tracks322, and use such servo information feedback to control the actuatorassembly 44 (illustrated in FIG. 1 ) to position the individual tapeheads 354A, 354B, 354C and/or the head assembly 330 as desired. In oneembodiment, a separate actuator assembly 44 and/or a separate controller46 can be included for each of the individual tape heads 354A, 354B,354C. With such design, the position and/or orientation of eachindividual tape head 354A, 354B, 354C can be controlled independently ofeach of the other tape heads 354A, 354B, 354C. Alternatively, in otherembodiments, a single actuator assembly 44 and/or a single controller 46can be utilized to control the position and/or orientation of more thanone tape head 354A, 354B, 354C.

FIG. 3A further illustrates each of the tape heads 354A, 354B, 354C in afirst position. In particular, in order to enable the tape heads 354A,354B, 354C to adapt to potential changes in tape width 352 due tochanges in environmental conditions such as temperature, dynamictemperature, humidity, tension, cartridge creep and/or aging, FIG. 3Aillustrates each of the tape heads 354A, 354B, 354C being initiallyoriented at a base head rotation angle 356 relative to transverse to thelength 316L (or longitudinal direction, illustrated as a two-headedarrow) of the magnetic tape 316. In certain non-excusive alternativeembodiments, the tape heads 354A, 354B, 354C can be initially orientedwith a base head rotation angle 356 of between approximately one degreeand 45 degrees relative to transverse to the length 316L of the magnetictape 316. More particularly, in some such embodiments, the tape heads354A, 354B, 354C can be initially oriented with a base head rotationangle 356 of between approximately five degrees and 45 degrees, fivedegrees and 40 degrees, five degrees and 35 degrees, five degrees and 30degrees, five degrees and 25 degrees, five degrees and 20 degrees, fivedegrees and 15 degrees, or five degrees and ten degrees relative totransverse to the length 316L of the magnetic tape 316. It isappreciated that the base head rotation angle 356 for each of the tapeheads 354A, 354B, 354C should be set such that the one or more servoelements 334 are initially effectively aligned with the one or moreservo tracks 322 on the magnetic tape 316, and the one or moreread/write elements 332 are effectively aligned with the one or moredata tracks 324 on the magnetic tape 316, prior to and/or at the startof use of the tape system 10 (illustrated in FIG. 1 ).

It is appreciated that any changes to the tape width 352 of the magnetictape 316, i.e. to an adjusted tape width 352A (illustrated in FIG. 3B),will again cause corresponding changes to a servo track spacing 358,i.e. to an adjusted servo track spacing 358A (illustrated in FIG. 3B),between the servo tracks 322 on the magnetic tape 316. In order todetermine the changes in servo track spacing 358 between the servotracks 322 on the magnetic tape 316 over time, any potential positionerror of the servo elements 334 relative to the servo tracks 322 can bedetermined at any time. In particular, the amount of compensation (orchange) can again be determined by averaging the position error of eachof the servo elements 334 to zero by tilting or rotating the tape head354A, 354B, 354C relative to the base head rotation angle 356. Stated inanother manner, if the tape width 352 of the magnetic tape 316 changesdue to any environmental conditions such as temperature, dynamictemperature, humidity, tension, cartridge creep and/or aging, therotation and/or orientation (or tilt) of each tape head 354A, 354B, 354Crelative to transverse to the length 316L of the magnetic tape 316 canbe independently servoed to compensate for any such changes. Thus, theactuator assembly 44 for each tape head 354A, 354B, 354C, under controlof the controller 46 for each tape head 354A, 354B, 354C, can move thetape heads 354A, 354B, 354C rotationally so that the servo elements 334are again accurately aligned with the servo tracks 322, and thus theread/write elements 332 can again be accurately aligned with the datatracks 324. As such, in various embodiments, the controller 46 is usedto control the actuator assembly 44 to control a rotational position ofeach tape head 354A, 354B, 354C of the head assembly 330 relative to themagnetic tape 316 based solely on servo information feedback.

More specifically, if it is determined that the tape width 352 of themagnetic tape 216, and thus the servo track spacing 358 between theservo tracks 322 on the magnetic tape 316, has increased (i.e. such thatthe magnetic tape 316 now has the adjusted tape width 352A, and theservo tracks 322 are spaced apart by the adjusted servo track spacing358A), then the controller 46 can control the actuator assembly 44associated with each tape head 354A, 354B, 354C to rotate such tape head354A, 354B, 354C so that the tape head 354A, 354B, 354C is oriented atan adjusted head rotation angle 360 relative to transverse to the length316L of the magnetic tape 316 that is different than, i.e. less than,the base head rotation angle 356. Such a situation is illustrated inFIG. 3B. In particular, FIG. 3B is a simplified schematic illustrationof the portion of the magnetic tape 316 and the tape head assembly 330illustrated in FIG. 3A, with the plurality of tape heads 354A, 354B,354C being shown in a second position, i.e. with each tape head 354A,354B, 354C having been reoriented to the adjusted head rotation angle360 relative to transverse to the length 316L of the magnetic tape 316.In the particular implementation illustrated in FIG. 3B, the adjustedhead rotation angle 360 is approximately zero degrees, with the tapeheads 354A, 354B, 354C being oriented transverse (or perpendicular) tothe length 316L of the magnetic tape 316. However, it is appreciatedthat the adjusted head rotation angle 360 can be other than zero degreesrelative to transverse to the length 316L of the magnetic tape 316.

Additionally or in the alternative, if it is determined that the tapewidth 352 of the magnetic tape 316, and thus the servo track spacing 358between the servo tracks 322 on the magnetic tape 316, has decreased(i.e. such that the magnetic tape 316 now has the adjusted tape width352A, and the servo tracks 322 are spaced apart by the adjusted servotrack spacing 358A), then the controller 46 can control the actuatorassembly 44 for each individual tape head 354A, 354B, 354C to rotatesuch tape heads 354A, 354B, 354C so that the tape head 354A, 354B, 354Cis oriented at an adjusted head rotation angle relative to transverse tothe length 316L of the magnetic tape 316 that is different than, i.e.greater than, the base head rotation angle 356.

Thus, it is appreciated that the adjusted head rotation angle 360 foreach tape head 354A, 354B, 354C relative to transverse to the length316L of the magnetic tape 316, as adjusted based on feedback from servoinformation due to changes in environmental conditions, can be greaterthan or less than the base head rotation angle 356. For example, incertain non-exclusive alternative embodiments, the adjusted headrotation angle 360 for each tape head 354A, 354B, 354C can be betweenapproximately zero degrees and 60 degrees relative to transverse to thelength 316L of the magnetic tape 316. More particularly, in some suchembodiments, each tape head 354A, 354B, 354C can be adjustedrotationally to an adjusted head rotation angle 360 of betweenapproximately zero degrees and 25 degrees relative to transverse to thelength 316L of the magnetic tape 316.

Additionally, in various embodiments, each tape head 354A, 354B, 354C ismovable and/or rotatable with the actuator assembly 44 relative to themagnetic tape 316 by between approximately one degree and 45 degreesfrom the base head rotation angle 356 to the adjusted head rotationangle 360. More particularly, in certain such non-exclusive embodiments,each tape head 354A, 354B, 354C is movable and/or rotatable with theactuator assembly 44 by at least approximately one degree, two degrees,three degrees, five degrees, seven degrees, ten degrees, 12 degrees, 15degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, or45 degrees from the base head rotation angle 356 to the adjusted headrotation angle 360.

It is appreciated that based on the particular designs of eachindividual tape head 354A, 354B, 354C, each tape head 354A, 354B, 354Cneed not be oriented to the same adjusted head rotation angle 360 inorder to effectively align the servo elements 334 of such tape heads354A, 354B, 354C to the servo tracks 322 on the magnetic tape 316.However, in various applications, if the design of each of the tapeheads 354A, 354B, 354C is substantially similar, then each tape head354A, 354B, 354C will typically be oriented at the same adjusted headrotation angle 360 in order to effectively align the servo elements 334of such tape heads 354A, 354B, 354C to the servo tracks 322 on themagnetic tape 316.

In certain embodiments, as illustrated herein, each tape head 354A,354B, 354C can be configured to rotate about a center of mass of suchtape head 354A, 354B, 354C. More particularly, in this embodiment, eachtape head 354A, 354B, 354C can be rotated by a respective actuatorassembly 44, under control of a respective controller 46, about a pivotpoint 362A, 362B, 362C that is positioned at the center of mass of suchtape head 354A, 354B, 354C. Alternatively, in other embodiments, eachtape head 354A, 354B, 354C can be configured to rotate about otherportions of such tape head 354A, 354B, 354C. For example, in certainsuch embodiments, each tape head 354A, 354B, 354C can be configured torotate about a centerline of one of the servo elements 334, e.g., eitherthe top servo element 334 or the bottom servo element 334 of such tapehead 354A, 354B, 354C. Still alternatively, in one embodiment, the tapeheads 354A, 354B, 354C can be configured to rotate collectively about asingle pivot point, e.g., at a center of mass of the head assembly 330in its entirety, which may coincide with a center of mass of a centrallypositioned tape head.

The embodiments described herein are not intended to be exhaustive or tolimit the invention to the precise forms disclosed in the followingdetailed description. Rather, the embodiments are chosen and describedso that others skilled in the art can appreciate and understand theprinciples and practices. As such, aspects have been described withreference to various specific and preferred embodiments and techniques.However, it should be understood that many variations and modificationsmay be made while remaining within the spirit and scope herein.

It is understood that although a number of different embodiments of themagnetic tape drive 12 and/or the tape head assembly 30 have beenillustrated and described herein, one or more features of any oneembodiment can be combined with one or more features of one or more ofthe other embodiments, provided that such combination satisfies theintent of the present invention.

While a number of exemplary aspects and embodiments of the magnetic tapedrive 12 and/or the tape head assembly 30 have been discussed above,those of skill in the art will recognize certain modifications,permutations, additions and sub-combinations thereof. It is thereforeintended that the following appended claims and claims hereafterintroduced are interpreted to include all such modifications,permutations, additions and sub-combinations as are within their truespirit and scope.

What is claimed is:
 1. A tape drive for use with a magnetic tapeincluding two spaced apart servo tracks and a first data track that ispositioned substantially between the two servo tracks along a length ofthe magnetic tape, the tape drive comprising: a first tape headincluding two spaced apart first servo elements that are each configuredto read one of the two servo tracks, and a first read/write element thatis configured to one of read data from the first data track and writedata to the first data track, the first tape head being positionable ata first base head rotation angle relative to transverse to the length ofthe magnetic tape; a first actuator assembly that is configured toselectively rotate the first tape head relative to the magnetic tapefrom the first base head rotation angle to a first adjusted headrotation angle that is different than the first base head rotationangle; a second tape head including two spaced apart second servoelements that are each configured to read one of the two servo tracks,and a second read/write element that is configured to one of read datafrom the first data track and write data to the first data track, thesecond tape head being positionable at a second base head rotation anglerelative to transverse to the length of the magnetic tape; a secondactuator assembly that is configured to selectively rotate the secondtape head relative to the magnetic tape from the second base headrotation angle to a second adjusted head rotation angle that isdifferent than the second base head rotation angle; and a controllerthat (i) controls the first actuator assembly to selectively rotate thefirst tape head relative to the magnetic tape from the first base headrotation angle to the first adjusted head rotation angle based solely onservo information from the two first servo elements reading the twoservo tracks; and (ii) controls the second actuator assembly toselectively rotate the second tape head relative to the magnetic tapefrom the second base head rotation angle to the second adjusted headrotation angle based solely on servo information from the two secondservo elements reading the two servo tracks, the controller controllingthe second actuator assembly independently of the first actuatorassembly.
 2. The tape drive of claim 1 wherein the controller (i)controls the first actuator assembly to selectively rotate the firsttape head relative to the magnetic tape from the first base headrotation angle to the first adjusted head rotation angle based solely ontiming-based servo information from the two first servo elements readingthe two servo tracks; and (ii) controls the second actuator assembly toselectively rotate the second tape head relative to the magnetic tapefrom the second base head rotation angle to the second adjusted headrotation angle based solely on timing-based servo information from thetwo second servo elements reading the two servo tracks.
 3. The tapedrive of claim 1 wherein the magnetic tape includes a plurality of datatracks that are positioned substantially between the two spaced apartservo tracks along the length of the magnetic tape; wherein the firsttape head includes a plurality of read/write elements that are eachconfigured to one of read data from one of the plurality of data tracksand write data to one of the plurality of data tracks; and wherein thesecond tape head includes a plurality of read/write elements that areeach configured to one of read data from one of the plurality of datatracks and write data to one of the plurality of data tracks.
 4. Thetape drive of claim 1 wherein at least one of the first base headrotation angle and the second base head rotation angle is betweenapproximately one degree and 45 degrees relative to transverse to thelength of the magnetic tape.
 5. The tape drive of claim 4 wherein atleast one of the first adjusted head rotation angle and the secondadjusted head rotation angle is between approximately zero degrees and60 degrees relative to transverse to the length of the magnetic tape. 6.The tape drive of claim 1 wherein at least one of the first base headrotation angle and the second base head rotation angle is betweenapproximately five degrees and 15 degrees relative to transverse to thelength of the magnetic tape.
 7. The tape drive of claim 6 wherein atleast one of the first adjusted head rotation angle and the secondadjusted head rotation angle is between approximately zero degrees and25 degrees relative to transverse to the length of the magnetic tape. 8.The tape drive of claim 1 wherein the two spaced apart servo tracks arespaced apart by a servo track spacing; wherein the first base headrotation angle is controlled by the controller so that each of the twospaced apart first servo elements are positioned to read one of the twospaced apart servo tracks that are spaced apart by the servo trackspacing; and wherein the second base head rotation angle is controlledby the controller so that each of the two spaced apart second servoelements are positioned to read one of the two spaced apart servo tracksthat are spaced apart by the servo track spacing.
 9. The tape drive ofclaim 8 wherein changes in environmental conditions cause a change inthe servo track spacing to an adjusted servo track spacing; wherein thefirst adjusted head rotation angle is controlled by the controller sothat each of the two spaced apart first servo elements are positioned toread one of the two spaced apart servo tracks that are spaced apart bythe adjusted servo track spacing; and wherein the second adjusted headrotation angle is controlled by the controller so that each of the twospaced apart second servo elements are positioned to read one of the twospaced apart servo tracks that are spaced apart by the adjusted servotrack spacing.
 10. The tape drive of claim 1 wherein the first tape headincludes a center of mass; and wherein the first actuator assembly isconfigured to rotate the first tape head relative to the magnetic tapeabout a first pivot point that is positioned at the center of mass ofthe first tape head.
 11. The tape drive of claim 10 wherein the secondtape head includes a center of mass; and wherein the second actuatorassembly is configured to rotate the second tape head relative to themagnetic tape about a second pivot point that is positioned at thecenter of mass of the second tape head.
 12. The tape drive of claim 1wherein the first actuator assembly is further configured to move thefirst tape head transversely relative to the magnetic tape; and whereinthe second actuator assembly is further configured to move the secondtape head transversely relative to the magnetic tape.
 13. A tape drivefor use with a magnetic tape including two spaced apart servo tracks anda first data track that are positioned along a length of the magnetictape, the tape drive comprising: a tape head assembly including (i) atleast two servo elements that are each configured to read one of the twoservo tracks, (ii) a first read/write element that is configured to oneof read data from the first data track and write data to the first datatrack, the first read/write element being positionable at a first baserotation angle relative to transverse to the length of the magnetictape, and (iii) a second read/write element that is configured to one ofread data from the first data track and write data to the first datatrack, the second read/write element being positionable at a second baserotation angle relative to transverse to the length of the magnetictape; an actuator assembly that is configured to (i) selectively rotatethe first read/write element relative to the magnetic tape from thefirst base rotation angle to a first adjusted rotation angle that isdifferent than the first base rotation angle, and (ii) selectivelyrotate the second read/write element relative to the magnetic tape fromthe second base rotation angle to a second adjusted rotation angle thatis different than the second base rotation angle; and a controller thatcontrols the actuator assembly to selectively and independently (i)rotate the first read/write element relative to the magnetic tape fromthe first base rotation angle to the first adjusted rotation angle basedsolely on servo information from the at least two servo elements readingthe two servo tracks, and (ii) rotate the second read/write elementrelative to the magnetic tape from the second base rotation angle to thesecond adjusted rotation angle based solely on servo information fromthe at least two servo elements reading the two servo tracks.
 14. Thetape drive of claim 13 wherein the controller controls the actuatorassembly to selectively and independently (i) rotate the firstread/write element relative to the magnetic tape from the first baserotation angle to the first adjusted rotation angle based solely ontiming-based servo information from the at least two servo elementsreading the two servo tracks, and (ii) rotate the second read/writeelement relative to the magnetic tape from the second base rotationangle to the second adjusted rotation angle based solely on timing-basedservo information from the at least two servo elements reading the twoservo tracks.
 15. The tape drive of claim 13 wherein the tape headassembly includes (i) a first tape head including two spaced apart firstservo elements that are each configured to read one of the two servotracks, and the first read/write element that is configured to one ofread data from the first data track and write data to the first datatrack; and (ii) a second tape head including two spaced apart secondservo elements that are each configured to read one of the two servotracks, and the second read/write element that is configured to one ofread data from the first data track and write data to the first datatrack.
 16. The tape drive of claim 13 wherein at least one of the firstbase rotation angle and the second base rotation angle is betweenapproximately one degree and 45 degrees relative to transverse to thelength of the magnetic tape.
 17. The tape drive of claim 16 wherein atleast one of the first adjusted rotation angle and the second adjustedrotation angle is between approximately zero degrees and 60 degreesrelative to transverse to the length of the magnetic tape.
 18. The tapedrive of claim 13 wherein the tape head assembly includes a center ofmass; and wherein the actuator assembly is configured to rotate the tapehead assembly relative to the magnetic tape about a pivot point that ispositioned at the center of mass of the tape head assembly.
 19. The tapedrive of claim 13 wherein the actuator assembly is further configured tomove the tape head assembly transversely relative to the magnetic tape.20. A tape drive for use with a magnetic tape including two spaced apartservo tracks that are spaced apart by a servo track spacing and aplurality of data tracks that are positioned substantially between thetwo servo tracks along a length of the magnetic tape, the tape drivecomprising: a first tape head including two spaced apart first servoelements that are each configured to read one of the two servo tracks,and a plurality of first read/write elements that are each configured toone of read data from one of the plurality of data tracks and write datato one of the plurality of data tracks, the first tape head beingpositionable at a first base head rotation angle of betweenapproximately one degree and 45 degrees relative to transverse to thelength of the magnetic tape; a first actuator assembly that isconfigured to selectively rotate the first tape head relative to themagnetic tape from the first base head rotation angle to a firstadjusted head rotation angle that is different than the first base headrotation angle, the first adjusted head rotation angle being betweenapproximately zero degrees and 60 degrees relative to transverse to thelength of the magnetic tape; a second tape head including two spacedapart second servo elements that are each configured to read one of thetwo servo tracks, and a plurality of second read/write elements that areeach configured to one of read data from one of the plurality of datatracks and write data to one of the plurality of data tracks, the secondtape head being positionable at a second base head rotation angle ofbetween approximately one degree and 45 degrees relative to transverseto the length of the magnetic tape; a second actuator assembly that isconfigured to selectively rotate the second tape head relative to themagnetic tape from the second base head rotation angle to a secondadjusted head rotation angle that is different than the second base headrotation angle, the second adjusted head rotation angle being betweenapproximately zero degrees and 60 degrees relative to transverse to thelength of the magnetic tape; and a controller that selectively andindependently (i) controls the first actuator assembly to selectivelyrotate the first tape head relative to the magnetic tape from the firstbase head rotation angle to the first adjusted head rotation angle basedsolely on servo information from the two first servo elements readingthe two servo tracks; and (ii) controls the second actuator assembly toselectively rotate the second tape head relative to the magnetic tapefrom the second base head rotation angle to the second adjusted headrotation angle based solely on servo information from the two secondservo elements reading the two servo tracks; wherein the first base headrotation angle is controlled by the controller so that each of the twospaced apart first servo elements are positioned to read one of the twospaced apart servo tracks that are spaced apart by the servo trackspacing; wherein the second base head rotation angle is controlled bythe controller so that each of the two spaced apart second servoelements are positioned to read one of the two spaced apart servo tracksthat are spaced apart by the servo track spacing; wherein changes inenvironment conditions cause a change in the servo track spacing to anadjusted servo track spacing; wherein the first adjusted head rotationangle is controlled by the controller so that each of the two spacedapart first servo elements are positioned to read one of the two spacedapart servo tracks that are spaced apart by the adjusted servo trackspacing; and wherein the second adjusted head rotation angle iscontrolled by the controller so that each of the two spaced apart secondservo elements are positioned to read one of the two spaced apart servotracks that are spaced apart by the adjusted servo track spacing.